Traditional metal core printed circuit boards (PCBs) are useful in a variety of applications due to their ability to dissipate heat away from electronic components, such as, for example, LEDs. Metal core PCBs (MCPCBs) are generally formed of a base metal, typically aluminum, copper, or alloys thereof, that acts as a heat sink to dissipate heat away from the integral electronic components of the PCB. Metal cores are often used as an alternative to common FR4 boards (fiberglass/epoxy composition material) or CEM3 circuit boards (polytetrafluoroethylene) because of their superior ability to dissipate heat.
Structurally, the PCB of an MCPCB must be attached to the heat sink in order to allow the heat sink to dissipate heat away from the PCB. Some conventional heat sinks have recesses on their surfaces depending on the geometry needed for a particular application. Heat sinks that have recesses can create manufacturing obstacles, as the PCB must be attached mechanically to the heat sink, such as with screws. This adds to the material and manufacturing cost of MCPCB and also creates multiple layers of thermal resistance between the PCB and the heat sink, thus decreasing the heat sink's capacity to dissipate heat away from the electronic components of the PCB.
One method of applying PCB directly onto a heat sink is through processing, whereby the dielectric and conductive layers (or other thermal or electronic layers) are applied directly to the heat sink, such as by screen printing using a thick film paste. However, such thick film pastes are not suitable for application to heat sinks with recessed cavities, as screen printing requires application to a substantially planar surface.
As such, there is a need for an improved method of applying dielectric (and conductive) layers directly to heat sinks with surfaces having recessed cavities, or otherwise non-planar surfaces. Methods which allow for direct application of dielectric compositions to heat sinks with recessed cavities would decrease material and manufacturing cost while maintaining the thermal dissipation properties of the heat sink.